This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Abstract

In the title compound, C14H12ClN3OS, the short exocyclic N—C bond lengths indicate resonance in the thiourea part of the mol­ecule. The title compound is stabilized by an intra­molecular N—HN hydrogen bond, which results in the formation of a six-membered ring. In addition, it shows a synperiplanar conformation between the thio­carbonyl group and the pyridine group. Inter­molecular N—HS and C—HO inter­actions are also present.

Our team focused on the synthesis, characterization, crystal structure, thermal
behavior and antimicrobial activity of new thiourea derivatives (Mansuroğlu
et al., 2008; Arslan et al., 2003a,
2003b,
2006a, 2006b, 2007; Uğur et al.,
2006; Özpozan et
al., 2000). In this article, we report the preparation and
characterization of a novel thiourea compound,
4-chloro-N-(6-methylpyridin-2-yl-carbamothioyl)benzamide (I), and its
crystal structure. The title compound was purified by re-crystallization from
ethanol:dichloromethane mixture (1:2) and characterized by elemental analysis.
The analytical data is consistent with the proposed structure given in Scheme
1.

The molecular structure and packing diagram are depicted in Figure 1 and 2,
respectively. The bond lengths and angles in the thiourea moiety are typical
for thiourea derivatives; the C8—S1 and C7—O1 bonds both show a typical
double-bond character with 1.655 (5) and 1.203 (6) Å, respectively. The short
bond lengths of the N1—C7, 1.395 (7); N1—C8, 1.376 (6) and N2—C8, 1.364 (6) Å bonds indicate partial double bond character. These results can be
explained by the existence of resonance in this part of the molecule. The
other C—N bond length is within the expected range.

A lot of substitute benzoylthiourea derivatives have cis-trans
configurations (Yusof, et al., 2008a,
2008b; Thiam, et
al., 2008; Xian, 2008; Dong, et al., 2008;
Duque, et al.,
2008). However, the title compound shows an intramolecular N—H···N
hydrogen
bond (Table 1) which results in the formation of a six membered ring
(N3—C9—N2—C8—N1—H1) and leads to a syn-periplanar
conformation between the thiocarbonyl group carbon atom and the pyridine group
nitrogen atom (Tutughamiarso & Bolte, 2007; Yue et al.,
2008). The
torsion angles in this region, C8—N2—C9—N3, 14.9 (9)° and
C9—N2—C8—N1, -7.2 (8)° confirm this conformation. This formation forces
the two amide hydrogen atoms to the opposite direction.

The carbonyl and thiocarbonyl part is essentially planar, as reflected by the
torsional angles O1—C7—N1—C8, C7—N1—C8—S1 and C7—N1—C8—N2 of
1.7 (9), 0.3 (8) and 179.3 (5) °, respectively. O1, C7, N1, C8 and S1 fragment
is also planar (maximum and mean deviations are 0.010 and 0.005 Å,
respectively).

The crystal packing is shown in Fig. 2. There are two intermolecular, N—H···S
and C—H···O, hydrogen bonds which connect molecules in chains parallel to
[100].

Experimental

The compound was prepared with a procedure similar to that reported in the
literature (Arslan et al., 2003b, 2006a).
A solution of
4-chloro-benzoyl chloride (0.01 mol) in acetone (50 cm3) was added dropwise
to a suspension of potassium thiocyanate (0.01 mol) in acetone (30 cm3). The
reaction mixture was heated under reflux for 30 min, and then cooled to room
temperature. A solution of 6-methylpyridin-2-amine (0.01 mol) in acetone (10 cm3) was added and the resulting mixture was stirred for 2 h. Hydrochloric
acid (0.1 N, 300 cm3) was added to the solution, which was then filtered.
The solid product was washed with water and purifed by recrystalization from
an ethanol:dichloromethane mixture (1:2). Anal. Calcd. for C14H12ClN3OS:
C, 55.0; H, 4.0; N, 13.7. Found: C, 55.1; H, 3.9; N, 13.7%.

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The threshold expression of F2 >
σ(F2) is used only for calculating R-factors(gt) etc.
and is not relevant to the choice of reflections for refinement.
R-factors based on F2 are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger.